We don’t need as much protein as we think we do

Vegetarians and vegans get sufficient protein from plant-based sources, including whole grains.Sheryl Julian/Globe Staff

It’s always a good time to think about eating more healthfully. And right now, after holiday gluttony, it’s particularly appropriate. One way to improve our diets is to understand how much protein we eat, what we really need, and where it comes from.

In general, Americans eat more protein than they need. The USDA recommended dietary allowance for people over age 19 is 56 grams of protein per day for men (this is equivalent to an 8-ounce burger made with 85 percent lean ground beef) and 46 grams for women (a small skinless chicken breast). What people are actually eating can be twice that. According to the USDA’s Center for Nutrition Policy and Promotion, the mean intake for men is 98 grams per day and for women, 67 grams. While eating more than the guidelines is unlikely to be a problem for most healthy people (the acceptable range is between 10 percent to 35 percent of total calories), much of the protein we like comes with hefty amounts of saturated fat, cholesterol, and/or calories.

Here is the protein content of some popular foods: A 5-ounce fillet of salmon is 35 grams; a 5-ounce can of tuna (drained), 25 grams; 5 ounces of lean beef, 35 to 40 grams. Note the moderate portion sizes and how these supply more than half the protein we need for an entire day. In non-meat sources, one cup of cooked beans, chickpeas, or peas provides about 15 grams of protein; edamame, about 20 grams; one egg, 6 grams; and 1 cup fat-free Greek yogurt or 1 cup low-fat cottage cheese, each about 20 grams. One cup of quinoa has 8 grams, as does ¼ cup of almonds.

Meat eaters often wonder how vegetarians and vegans get sufficient protein. They’re getting it from plant-based sources: 1 cup of whole-grain breakfast cereal has 6 to 14 grams of protein; 3 ounces of tofu, 8 grams; 1 cup of cooked whole grains, about 6 grams; 1 cup of cooked lentils, 18 grams; 1 cup of cooked spinach, 5 grams; 2 tablespoons of peanut butter, 8 grams, a slice of whole-wheat bread, 4 grams.

“We like protein,” says James Tillotson about the American diet. The professor of food policy and international business at Tufts University explains our fondness for animal protein. “Humans like the taste of meat,” he says. Even with meat typically costing more than other foods, he says, “If we have the income, we buy it. That’s a basic underlying trend that as a country gets richer, the diet shifts to animal protein.” This occurred in the United States after World War II, and it’s increasingly evident in Japan and China.

In this country, meat and poultry account for 70 percent of the protein foods (not including dairy) consumed, says Trish Britten, nutritionist with the Center for Nutrition Policy and Promotion. Animal-based foods are considered complete protein sources, while most plant foods are incomplete, meaning they lack one or more amino acids, which are the building blocks of protein. However, eating a variety of vegetables, legumes, and grains throughout the day (it doesn’t have to be in the same meal) will provide adequate amounts of all the essential amino acids.

Britten recommends that people vary their sources of protein to get a range of important nutrients. She suggests choosing from a list that includes poultry, seafood, lean meat, eggs, soy products, dairy, legumes, grains, nuts, and seeds. “Eat moderate portions of these,” she says, to stay within daily calorie guidelines. “There is too much of a good thing.”

In 2011, the USDA came out with MyPlate (www.choosemyplate.gov), which reflects the proportions of key food groups people should eat. The recommended plate contains a little over one-quarter each of vegetables and grains, and a little less than one-quarter each of lean protein and fruit, along with a small amount of dairy. “It’s a very simple image that people can use,” says Britten.

A similar, but more detailed Healthy Eating Plate was developed by Harvard Health Publications and the Harvard School of Public Health, emphasizing vegetables, adding healthy oils, and advising limited refined grains, red meat, and dairy. (www.health.harvard.edu/plate/healthy-eating-plate)

Rather than fill up on protein in one sitting, Massachusetts General Hospital dietitian Molly Cleary recommends eating small portions at meals, which helps you feel full longer. “People think they need a lot more than they do,” she says.

Another acceptable daily guideline for protein is weight-based: 0.8 grams of protein per kilogram of body weight or about 8 grams for every 22 pounds. The formula is based on healthy body weights and does not apply to people who are obese. With MyPlate as a guideline, Cleary says to aim for one-third each vegetables, lean protein, and whole grains, and eat fruit for snacks. “Any shift toward more vegetables is a good thing,” she adds.

To incorporate more plant foods into your diet, mix them with foods you like, such as pasta, grains, soups, and stews, or make them a center-of-the-plate bed for a small, lean piece of poultry, fish, meat, or tofu. Adding beans to your meals is easy: make chili, soup, quesadillas, burritos, veggie burgers, and bean spreads. Or toss beans, lentils, or peas into green or grain salads.

In January, when you’re thinking carefully about what you eat, it’s easy to be confused by fad diets and unproven health claims. What the nutrition experts agree on is to stick to real (unprocessed) foods, choose lean protein, read nutrition labels so you know what you’re eating, and be mindful of portion size. Cutting down can be the hardest piece to put into place.